Display devices for mobile phones and the like adopt a method in which a display ON signal and a display OFF signal are transmitted to a display device to switch the display device between a displaying state and a non-displaying state.
FIG. 4 is a block diagram showing a structure of a display device employed in conventional mobile phones and the like. The display device includes a liquid crystal display (this display will be referred to as “LCD” hereinafter) panel 31, which is a display section, first to third source drivers 33, 35, 37 to drive respective pixels of the LCD panel 31, and a gate driver 39.
To switch a display state of the LCD panel 31 from ON to OFF in the display device, an OFF signal is fed into the first to third source drivers 33, 35, 37 and the gate driver 39. As a result, the first to third source drivers 33, 35, 37 and the gate driver 39 stop operating, and the display state of the LCD panel 31 becomes OFF.
On the other hand, to switch the display state of the LCD panel 31 from OFF to ON, an ON signal is fed into the first to third source drivers 33, 35, 37 and the gate driver 39. As a result, the first to third source drivers 33, 35, 37 and the gate driver 39 start operating, and the display state of the LCD panel 31 becomes ON.
The display device disclosed in Publication 1 is known as a concrete way to switch the display state in the manner as described above. Specifically, the display device includes a circuit that switches the display state. The circuit is constituted of, for example, a combination of a latch circuit, an AND circuit, and the like. A user presses a display ON/OFF key of a keyboard to activate a program to switch the display state of a CRT that is a display section. The display device having the circuit allows the display state to be switched promptly. Further, the display device does not turn ON/OFF a power source for the entire display device but controls only an ON/OFF state of a display. Thus, for example a power-saving mode in which only a display is turned OFF is realized.
Publication 2 discloses a technique by which operation of a source driver (this driver is referred to as “drain driver” in Publication 2) is synchronized with a rise or a fall of a vertical synchronizing signal (this signal will be referred to as “VSYNC” hereinafter).    [Publication 1] Japanese Unexamined Patent Publication No. 311517/1988 (Tokukaisho 63-311517) (Publication Date: Dec. 20, 1988)    [Publication 2] Japanese Unexamined Patent Publication No. 174785/2001 (Tokukai 2001-174785) (Publication Date: Jun. 29, 2001)